I think this was in one of the DVD commentaries somewhere. Centauri hair was originally going to be more tightly curled -- like the guards seen in "Signs and Portents" -- and not stand up at all. But Peter Jurasik and his hairdresser decided to play a joke, put Peter's hair up in the style we now know so well, and went out to say to JMS "What do you think?" -- assuming he'd laugh, they'd laugh, and then go back to the way he'd originally planned. But JMS says, "Okay, do it that way," and JMS is God on set, so they did.

Turns out JMS, still finding his feet and his confidence, thought at the time, "Well, if that's what the actor wants, I guess it's okay..." -- not realizing that Peter wasn't serious.

Going by the Season One outtakes, I'm guessing that within a couple months they knew each other well enough that it would have been a big laugh and then they'd gone about their business. But it was a little too soon in their relationship.

I'm doing all this from memory. Somebody may have a more accurate version of the tale.